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Genet Res

Title:		Mismatch repair and the accumulation of deleterious mutations influence the competitive advantage of MAT (mating type) heterozygosity in the yeast Saccharomyces cerevisiae
Author(s):		Selk E; Wills C;
Address:		"Department of Biology, University of California, San Diego, La Jolla 92093-0116, USA"
Journal Title:		Genet Res
Year:		1998
Volume:		71
Issue:		1
Page Number:		1 - 10
DOI:		10.1017/s001667239700308x
ISSN/ISBN:		0016-6723 (Linking)
Abstract:		"Competitions between matched pairs of diploid strains of Saccharomyces cerevisiae, one capable of undergoing sexual recombination (MAT-heterozygous) and the other not (MAT-homozygous), have proved useful for measuring the effects of mitotic and meiotic recombination and DNA repair on competitive ability in this organism. Overall competitive differences between the strains can be enhanced by converting them to petites (aerobic respiration incompetent). Here we report the results of competitions between pairs of strains that also differ in their ability to undergo mismatch repair. In petite strains, the growth rates of mismatch-repair defective strains declined over time regardless of their MAT genotype. Mismatch-repair proficient MAT-heterozygous strains did not show a decline, while repair-deficient MAT-homozygous strains did. The decline appears to be due to the accumulation of deleterious mutations of small effect, which can be corrected by MAT-heterozygous strains having intact mismatch repair. The relative competitive abilities of MAT-heterozygous and MAT-homozygous strains diverged during the course of the competitions, and the variance of this divergence increased significantly when mismatch repair was defective. This large stochastic component indicates that a relatively small number of deleterious mutations may be involved. The accumulation of deleterious mutations and their subsequent repair may have a bearing on the origin of sex in this organism"
Keywords:		*DNA Repair *Heterozygote Homozygote Mating Factor *Mutation Nucleic Acid Heteroduplexes Peptides/*genetics Pheromones/genetics Saccharomyces cerevisiae/*genetics/growth & development;
Notes:		"MedlineSelk, E Wills, C eng 1-R03 AI41370-01/AI/NIAID NIH HHS/ Research Support, U.S. Gov't, Non-P.H.S. Research Support, U.S. Gov't, P.H.S. England 1998/07/23 Genet Res. 1998 Feb; 71(1):1-10. doi: 10.1017/s001667239700308x"